The article describes the health benefits of the hearty belly laugh recommended by doctors. A 2016 study, "The Laughter Prescription," showed that the amount of laughter is linked to the immune system and increases the activity of natural killer cells (NK cells), which destroy cancer and virus-infected cells[1]. One hour of a funny video increases NK cell levels, heart rate and oxygen in the body[1]. Laughter lowers blood pressure, releases nitric oxide, which relaxes blood vessels and reduces the risk of stroke and heart attack[1][3]. A systematic review and meta-analysis confirms that spontaneous laughter reduces cortisol levels by 31.9% compared to normal activities, even a one-off session by 36.7%[2]. Physician Michael Miller prescribes patients one good belly laugh a day to induce tears of joy and relaxation[3]. In addition, laughter increases pain tolerance, improves blood flow, burns calories like a slow walk, and releases endorphins[1][4][5]. These effects boost immunity, reduce stress hormones, and improve mood[1][2][5].